The Herrera film

In 1880 Samuel Garman reported a new species of sea turtle he called Thalassochelys kempii (now called Lepidochelys kempii). A fisherman from Florida named Richard M. Kemp had brought Garman two specimens of a turtle known as the “bastard” turtle because it was thought by locals to be a cross between a loggerhead and green sea turtle. Garman decided that “in consideration of the great interest Mr. Kemp takes in matters pertaining to natural history, it is most appropriate that the species he has been the means of bringing into notice should bear his name” and thus gave this newly described species the common name of “Kemp’s Gulf Turtle”. The current generally accepted English common name is “Kemp’s ridley”; and it is “tortuga lora” in Spanish.

Samuel Garman, from http://en.wikipedia.org/wiki/Samuel_Garman

Kemp noted to Garman that “The Bastard Turtle are common. We know that they come on the beach to lay in the months of December, January, and February, but cannot tell how often, or how many eggs they lay at a time. They can be secured quite readily but are not sought for.” Interestingly, no Kemp’s ridley nesting beaches currently exist in the United States outside of Texas .

In 1961 researchers knew about Kemp’s ridley but had no idea where it nested. If it behaved like its congener, the olive ridley, it likely came up en masse in what are termed arribadas. All other species of sea turtles nest individually, but ridleys appear to coordinate their efforts and wait offshore for some unknown clue that tells them to come ashore. Well known sea turtle biologists like Archie Carr and Henry Hildebrand scoured the Mexican Gulf coast looking for signs of nesting ridleys. They found some shells and other indications that indeed there was some nesting but nothing to account for the numbers of turtles that researchers were encountering in the Gulf of Mexico. Dr. Carr later recalled that he and his family, on their way back from his work in Tortugero, Costa Rica, “had stopped at every coastal town accessible from the Pan-American Highway and at each stop I had gone through a routine ransacking of the place for turtle clues. I searched the fish markets, walked the beaches looking for tracks, poked about garbage dumps after shells and bones, and quizzed all the fishermen I could stimulate to talk, to hear what they would tell.”

But in 1961 Dr. Hildebrand made an important discovery: a film made by a Mexican engineer named Andrés Herrera. Mr. Herrera had heard of an immense turtle nesting spectacle that occurred just north of his home town of Tampico, Tamaulipas. He was a pilot and decided he would try to find this event by flying over the coast. He brought along a friend who was a photographer and wanted to get it on film. By the 24th day of flying up and down the coast the photographer gave up, loaned Mr. Herrera his video camera and went back home to Mexico City. On the 25th day, Mr. Herrera filmed a nesting event so remarkable to the understanding of Kemp’s ridley natural history that it has probably been studied almost as much as the Zapruder film. You can see a portion of the film here:

Biologists have estimated that somewhere around 40,000 females came ashore during that one arribada. By 1982 that number had plummeted to 702 nests total. For many years biologists thought the Kemp’s ridleys nested no place else in any significant numbers and this beach, Rancho Nuevo in Tamaulipas, was its only nesting population. With much hard work and international collaborations, Rancho Nuevo has made an impressive recovery. The population at Rancho Nuevo now appears to be hovering around 20,000 nests per year, with the exception of 2010.

But what about 2010 made the counts drop so drastically? The BP Deepwater Horizon oil disaster happened on April 20 of that same year, at the start of the Kemp’s nesting season. While we can’t be certain that the two are linked, there were about 200 Kemp’s known to die as a direct result of the oil spill. So, it is quite likely that the oil spill interrupted the normal behavior of Kemp’s in the Gulf of Mexico during that year. The good news is that the nesting numbers seem to have rebounded in the following years.